The present invention relates to an automatic transmission, and more specifically to an automatic transmission arranged to sense an input speed.
Recently, an automatic transmission is arranged to improve the quality of shift control by sensing the input rotation speed and the output rotation speed, and examining the gear ratio accurately during the process of shifting.
U.S. Pat. No. 5,938,559 (≈JP10030688 A) discloses an automatic transmission including three planetary gears for providing five forward speeds and one reverse speed. In this transmission, the input shaft is located at the center, and enclosed by a rotating member, so that the direct detection of the input rotation speed is not easy.